package edu.ustb.mis.dm.util;

import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import org.apache.commons.lang.StringUtils;

/**
 * 反射工具类. 提供调用getter/setter方法, 访问私有变量, 调用私有方法, 获取泛型类型Class, 被AOP过的真实类等工具函数.
 * 
 * @author calvin
 */
public abstract class ReflectionUtils {
	public static final String CGLIB_CLASS_SEPARATOR = "$$";

	/**
	 * 将反射时的checked exception转换为unchecked exception.
	 */
	public static RuntimeException convertReflectionExceptionToUnchecked(final Exception e) {
		if ( (e instanceof IllegalAccessException) || (e instanceof IllegalArgumentException) || (e instanceof NoSuchMethodException)) {
			return new IllegalArgumentException("Reflection Exception.", e);
		} else if (e instanceof InvocationTargetException) {
			return new RuntimeException("Reflection Exception.", ((InvocationTargetException)e).getTargetException());
		} else if (e instanceof RuntimeException) {
			return (RuntimeException)e;
		}
		return new RuntimeException("Unexpected Checked Exception.", e);
	}

	/**
	 * 循环向上转型, 获取对象的DeclaredField, 并强制设置为可访问. 如向上转型到Object仍无法找到, 返回null.
	 */
	public static Field getAccessibleField(final Object obj, final String fieldName) {
		for (Class<?> superClass = obj.getClass(); superClass != Object.class; superClass = superClass.getSuperclass()) {
			try {
				final Field field = superClass.getDeclaredField(fieldName);
				field.setAccessible(true);
				return field;
			} catch (final NoSuchFieldException e) {// NOSONAR
				// Field不在当前类定义,继续向上转型
			}
		}
		return null;
	}

	/**
	 * 循环向上转型, 获取对象的DeclaredMethod,并强制设置为可访问. 如向上转型到Object仍无法找到, 返回null. 用于方法需要被多次调用的情况. 先使用本函数先取得Method,然后调用Method.invoke(Object
	 * obj, Object... args)
	 */
	public static Method getAccessibleMethod(final Object obj, final String methodName, final Class<?>... parameterTypes) {
		for (Class<?> superClass = obj.getClass(); superClass != Object.class; superClass = superClass.getSuperclass()) {
			try {
				final Method method = superClass.getDeclaredMethod(methodName, parameterTypes);
				method.setAccessible(true);
				return method;
			} catch (final NoSuchMethodException e) {// NOSONAR
				// Method不在当前类定义,继续向上转型
			}
		}
		return null;
	}

	/**
	 * 直接读取对象属性值, 无视private/protected修饰符, 不经过getter函数.
	 */
	public static Object getFieldValue(final Object obj, final String fieldName) {
		final Field field = getAccessibleField(obj, fieldName);
		if (field == null) {
			throw new IllegalArgumentException("Could not find field [" + fieldName + "] on target [" + obj + "]");
		}
		Object result = null;
		try {
			result = field.get(obj);
		} catch (final IllegalAccessException e) {
			System.err.println("不可能抛出的异常" + e.getMessage());
		}
		return result;
	}

	/**
	 * 通过反射, 获得Class定义中声明的父类的泛型参数的类型. 如无法找到, 返回Object.class. eg. public UserDao extends HibernateDao<User>
	 * 
	 * @param clazz The class to introspect
	 * @return the first generic declaration, or Object.class if cannot be determined
	 */
	@SuppressWarnings("unchecked")
	public static <T>Class<T> getSuperClassGenricType(@SuppressWarnings("rawtypes") final Class clazz) {
		return getSuperClassGenricType(clazz, 0);
	}

	/**
	 * 通过反射, 获得Class定义中声明的父类的泛型参数的类型. 如无法找到, 返回Object.class. 如public UserDao extends HibernateDao<User,Long>
	 * 
	 * @param clazz clazz The class to introspect
	 * @param index the Index of the generic ddeclaration,start from 0.
	 * @return the index generic declaration, or Object.class if cannot be determined
	 */
	@SuppressWarnings("rawtypes")
	public static Class getSuperClassGenricType(final Class clazz, final int index) {
		final Type genType = clazz.getGenericSuperclass();
		if (! (genType instanceof ParameterizedType)) {
			System.out.println(clazz.getSimpleName() + "'s superclass not ParameterizedType");
			return Object.class;
		}
		final Type[] params = ((ParameterizedType)genType).getActualTypeArguments();
		if ( (index >= params.length) || (index < 0)) {
			System.out.println("Index: " + index + ", Size of " + clazz.getSimpleName() + "'s Parameterized Type: " + params.length);
			return Object.class;
		}
		if (! (params[index] instanceof Class)) {
			System.out.println(clazz.getSimpleName() + " not set the actual class on superclass generic parameter");
			return Object.class;
		}
		return (Class)params[index];
	}

	/**
	 * 对于被cglib AOP过的对象, 取得真实的Class类型.
	 */
	public static Class<?> getUserClass(final Class<?> clazz) {
		if ( (clazz != null) && clazz.getName().contains(CGLIB_CLASS_SEPARATOR)) {
			final Class<?> superClass = clazz.getSuperclass();
			if ( (superClass != null) && !Object.class.equals(superClass)) {
				return superClass;
			}
		}
		return clazz;
	}

	/**
	 * 调用Getter方法.
	 */
	public static Object invokeGetterMethod(final Object obj, final String propertyName) {
		final String getterMethodName = "get" + StringUtils.capitalize(propertyName);
		return invokeMethod(obj, getterMethodName, new Class[]{}, new Object[]{});
	}

	/**
	 * 直接调用对象方法, 无视private/protected修饰符. 用于一次性调用的情况.
	 */
	public static Object invokeMethod(final Object obj, final String methodName, final Class<?>[] parameterTypes, final Object[] args) {
		final Method method = getAccessibleMethod(obj, methodName, parameterTypes);
		if (method == null) {
			throw new IllegalArgumentException("Could not find method [" + methodName + "] on target [" + obj + "]");
		}
		try {
			return method.invoke(obj, args);
		} catch (final Exception e) {
			throw convertReflectionExceptionToUnchecked(e);
		}
	}

	/**
	 * 调用Setter方法.使用value的Class来查找Setter方法.
	 */
	public static void invokeSetterMethod(final Object obj, final String propertyName, final Object value) {
		invokeSetterMethod(obj, propertyName, value, null);
	}

	/**
	 * 调用Setter方法.
	 * 
	 * @param propertyType 用于查找Setter方法,为空时使用value的Class替代.
	 */
	public static void invokeSetterMethod(final Object obj, final String propertyName, final Object value, final Class<?> propertyType) {
		final Class<?> type = propertyType != null ? propertyType : value.getClass();
		final String setterMethodName = "set" + StringUtils.capitalize(propertyName);
		invokeMethod(obj, setterMethodName, new Class[]{type}, new Object[]{value});
	}

	/**
	 * 直接设置对象属性值, 无视private/protected修饰符, 不经过setter函数.
	 */
	public static void setFieldValue(final Object obj, final String fieldName, final Object value) {
		final Field field = getAccessibleField(obj, fieldName);
		if (field == null) {
			throw new IllegalArgumentException("Could not find field [" + fieldName + "] on target [" + obj + "]");
		}
		try {
			field.set(obj, value);
		} catch (final IllegalAccessException e) {
			System.err.println("不可能抛出的异常" + e.getMessage());
		}
	}
}
